Beijing Subway Adds "Green Power" as Domestic Oil-Free Air Compressor Technology Lands on Yizhuang Line
Oct 20 , 2025
Reporters learned from Beijing MTR Operation Corporation that recently, the domestic oil-free air compressor air supply system for the braking system, which is adapted to the DKZ32 electric trains of Beijing Subway Yizhuang Line, has been operating stably on Trains 004 and 013 of Yizhuang Line for more than 3 months. This marks a key phased achievement in the adaptability research of oil-free air compressors for subways.
It is reported that the oil-free piston air compressor air supply system no longer relies on lubricating oil in the process of compressing air. It avoids pollution from oil stains on key components such as the braking system and air springs at the source, which not only reduces the impact on the environment but also makes train operation more in line with the "green and low-carbon" urban transportation development concept. In terms of structural design, it is more concise with low system complexity. It requires almost no additional maintenance during the train's overhaul cycle, reducing maintenance workload and the risk of failures caused by improper maintenance. In the long run, the "maintenance-free" feature of oil-free air compressors directly saves a large amount of operation and maintenance costs. In addition, their working efficiency is not limited and their reliability is higher, so the whole-life cycle cost is much lower than that of oil-lubricated air compressors.
After project initiation, design liaison, prototype trial production, hanging and loading, whole-train type test and train commissioning, the two trains equipped with oil-free air compressors were officially put into passenger operation on May 26 and July 30, 2025 respectively. During the R&D process, the R&D team focused on tackling key technologies and solved the problems encountered in the selection of friction pairs and the surface treatment of cylinder inner walls. This ensures that the air supply system, under the working condition without lubricating oil, can achieve mutual sealing between the two components and ensure that the air displacement attenuation of the air compressor does not exceed 5% within a service life of 10,000 hours (8 years).
As Trains 004 and 013 of Yizhuang Line have completed the 10-kilometer operation mileage assessment, the oil-free air compressor air supply system will undergo more comprehensive performance verification in the next step.
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